They were more concerned about his injury than collecting evidence. It is obvious on the film that the cop was distraught over what he had done.
Sure they were...
Pardon me, n00b, but what evidence do you have that it was drugs that this guy threw on the ground? If you don’t have direct evidence it was drugs, then I would encourage you to look up the word ‘libel’.
They were? Look at the video again! While he's lying unconcious, the one cop holds the kid in a straight arm lock which is used to immobilize a prone suspect then they roll him over one way then back and again use the straightarm hold.......while he's still unconscious.........At that point in time they were not concerned about any injury. Look at 1:29 of the video again when they grab his arm and pull him back onto his back. Yea, that's certainly great technique on how to examine an unconscious individual who may have just sustained a severe neck or brain injury.........